/* ============================================
   陈虎个人展示网站 - 主样式
   iOS 官网风格 / 白色主题
   ============================================ */

/* ---------- CSS Variables ---------- */
:root {
  --color-bg: #ffffff;
  --color-bg-secondary: #f5f5f7;
  --color-bg-tertiary: #fbfbfd;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-text-tertiary: #86868b;
  --color-accent: #0071e3;
  --color-accent-hover: #0077ed;
  --color-border: #d2d2d7;
  --color-border-light: #e8e8ed;
  --color-success: #34c759;
  --color-warning: #ff9500;
  --color-danger: #ff3b30;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.1);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --nav-height: 48px;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.47;
  font-size: 17px;
  overflow-x: hidden;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

img {
  max-width: 100%;
  display: block;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

ul, ol {
  list-style: none;
}

/* ---------- Icon System ---------- */
.icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1em;
  height: 1em;
  vertical-align: middle;
  flex-shrink: 0;
}

.icon svg {
  width: 100%;
  height: 100%;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.icon-brand svg {
  fill: currentColor;
  stroke: none;
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  z-index: 1000;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.nav-inner {
  max-width: 1024px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 22px;
}

.nav-logo {
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.nav-logo a {
  color: var(--color-text);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a {
  font-size: 12px;
  color: var(--color-text-secondary);
  font-weight: 400;
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--color-text);
}

.nav-menu-btn {
  display: none;
  width: 32px;
  height: 32px;
  align-items: center;
  justify-content: center;
  color: var(--color-text);
  font-size: 18px;
}

/* ---------- Off-canvas Sidebar ---------- */
.sidebar-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-normal), visibility var(--transition-normal);
  z-index: 1999;
}

.sidebar-overlay.active {
  opacity: 1;
  visibility: visible;
}

.sidebar {
  position: fixed;
  top: 0;
  right: -320px;
  width: 300px;
  height: 100vh;
  background: var(--color-bg);
  z-index: 2000;
  transition: right var(--transition-normal);
  box-shadow: var(--shadow-xl);
  display: flex;
  flex-direction: column;
}

.sidebar.active {
  right: 0;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid var(--color-border-light);
}

.sidebar-header h3 {
  font-size: 17px;
  font-weight: 600;
}

.sidebar-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  font-size: 18px;
  border-radius: 50%;
  transition: background var(--transition-fast);
}

.sidebar-close:hover {
  background: var(--color-bg-secondary);
}

.sidebar-nav {
  flex: 1;
  padding: 16px 0;
  overflow-y: auto;
}

.sidebar-nav-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 24px;
  color: var(--color-text);
  font-size: 15px;
  transition: background var(--transition-fast);
  cursor: pointer;
}

.sidebar-nav-item:hover {
  background: var(--color-bg-secondary);
}

.sidebar-nav-item .icon {
  font-size: 18px;
  color: var(--color-text-secondary);
}

.sidebar-nav-item .nav-arrow {
  margin-left: auto;
  font-size: 14px;
  color: var(--color-text-tertiary);
}

.sidebar-section-title {
  padding: 20px 24px 8px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-tertiary);
}

.sidebar-footer {
  padding: 20px 24px;
  border-top: 1px solid var(--color-border-light);
  font-size: 12px;
  color: var(--color-text-tertiary);
}

/* ---------- Hero Section ---------- */
.hero {
  padding: calc(var(--nav-height) + 80px) 22px 100px;
  text-align: center;
  background: var(--color-bg);
}

.hero-eyebrow {
  font-size: 17px;
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.hero-title {
  font-size: 56px;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.07;
  margin-bottom: 16px;
  background: linear-gradient(180deg, #1d1d1f 0%, #434345 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 24px;
  font-weight: 400;
  color: var(--color-text-secondary);
  letter-spacing: -0.01em;
  line-height: 1.3;
  max-width: 640px;
  margin: 0 auto 40px;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 980px;
  font-size: 17px;
  font-weight: 400;
  transition: all var(--transition-fast);
  cursor: pointer;
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #fff;
}

.btn-secondary {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
}

.btn-secondary:hover {
  background: var(--color-accent);
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--color-accent);
  padding: 12px 16px;
}

.btn-ghost:hover {
  text-decoration: underline;
}

.btn-lg {
  padding: 16px 32px;
  font-size: 19px;
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ---------- Section Common ---------- */
.section {
  padding: 100px 22px;
}

.section-alt {
  background: var(--color-bg-secondary);
}

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 60px;
}

.section-eyebrow {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}

.section-title {
  font-size: 40px;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-bottom: 16px;
}

.section-desc {
  font-size: 19px;
  color: var(--color-text-secondary);
  line-height: 1.4;
}

.container {
  max-width: 1024px;
  margin: 0 auto;
}

/* ---------- Skills Grid ---------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
}

.skill-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
  border: 1px solid var(--color-border-light);
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.skill-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 32px;
  color: var(--color-accent);
}

.skill-name {
  font-size: 19px;
  font-weight: 600;
  margin-bottom: 6px;
  letter-spacing: -0.01em;
}

.skill-desc {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.4;
}

/* ---------- Tech Stack ---------- */
.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-top: 40px;
}

.tech-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: 980px;
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text);
  transition: all var(--transition-fast);
}

.tech-badge:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-2px);
}

.tech-badge .icon {
  font-size: 18px;
}

/* ---------- Achievements ---------- */
.achievements-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.achievement-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: 36px 32px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.achievement-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.achievement-number {
  font-size: 48px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: 12px;
}

.achievement-title {
  font-size: 19px;
  font-weight: 600;
  margin-bottom: 8px;
}

.achievement-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* ---------- Feature Cards (for about section) ---------- */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-lg);
  padding: 40px 36px;
  border: 1px solid var(--color-border-light);
  transition: all var(--transition-normal);
}

.feature-card:hover {
  box-shadow: var(--shadow-md);
}

.feature-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 26px;
  color: var(--color-accent);
  margin-bottom: 20px;
  background: rgba(0, 113, 227, 0.08);
  border-radius: var(--radius-md);
}

.feature-title {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.feature-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* ---------- Footer ---------- */
.footer {
  background: var(--color-bg-secondary);
  padding: 40px 22px;
  border-top: 1px solid var(--color-border-light);
}

.footer-inner {
  max-width: 1024px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-text {
  font-size: 12px;
  color: var(--color-text-tertiary);
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  font-size: 12px;
  color: var(--color-text-secondary);
}

.footer-links a:hover {
  color: var(--color-text);
}

/* ---------- Page Header (inner pages) ---------- */
.page-header {
  padding: calc(var(--nav-height) + 60px) 22px 50px;
  text-align: center;
  background: var(--color-bg);
}

.page-header h1 {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.page-header p {
  font-size: 19px;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ---------- Breadcrumb ---------- */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 20px 22px;
  max-width: 1024px;
  margin: 0 auto;
  font-size: 13px;
  color: var(--color-text-tertiary);
}

.breadcrumb a {
  color: var(--color-text-secondary);
}

.breadcrumb a:hover {
  color: var(--color-accent);
}

.breadcrumb .icon {
  font-size: 12px;
}

.breadcrumb-current {
  color: var(--color-text);
  font-weight: 500;
}

/* ---------- Service Category Cards ---------- */
.service-categories {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  padding: 0 22px 80px;
  max-width: 1024px;
  margin: 0 auto;
}

.service-category-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  border: 1px solid var(--color-border-light);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-decoration: none;
  color: var(--color-text);
}

.service-category-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  color: var(--color-text);
}

.service-category-icon {
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  background: rgba(0, 113, 227, 0.08);
  color: var(--color-accent);
  border-radius: var(--radius-md);
  margin-bottom: 24px;
}

.service-category-title {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.service-category-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.5;
  margin-bottom: 20px;
  flex: 1;
}

.service-category-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 15px;
  font-weight: 500;
  color: var(--color-accent);
}

/* ---------- OS Selection Cards ---------- */
.os-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  padding: 0 22px 80px;
  max-width: 800px;
  margin: 0 auto;
}

.os-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: 48px 32px;
  border: 2px solid var(--color-border-light);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-normal);
  text-decoration: none;
  color: var(--color-text);
}

.os-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  color: var(--color-text);
}

.os-card-icon {
  width: 72px;
  height: 72px;
  margin: 0 auto 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 42px;
  color: var(--color-text);
}

.os-card-title {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 8px;
}

.os-card-desc {
  font-size: 14px;
  color: var(--color-text-secondary);
}

/* ---------- Version Selection ---------- */
.version-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  padding: 0 22px 80px;
  max-width: 900px;
  margin: 0 auto;
}

.version-card {
  background: var(--color-bg);
  border-radius: var(--radius-md);
  padding: 28px 20px;
  border: 1.5px solid var(--color-border-light);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: var(--color-text);
}

.version-card:hover {
  border-color: var(--color-accent);
  background: rgba(0, 113, 227, 0.03);
  transform: translateY(-2px);
  color: var(--color-text);
}

.version-card-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 4px;
}

.version-card-sub {
  font-size: 12px;
  color: var(--color-text-tertiary);
}

/* ---------- Service Detail List ---------- */
.service-detail-list {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 22px 80px;
}

.service-item {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 24px 28px;
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.service-item:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}

.service-item-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  background: rgba(0, 113, 227, 0.08);
  color: var(--color-accent);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.service-item-content {
  flex: 1;
}

.service-item-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 4px;
}

.service-item-desc {
  font-size: 14px;
  color: var(--color-text-secondary);
}

.service-item-arrow {
  font-size: 18px;
  color: var(--color-text-tertiary);
  flex-shrink: 0;
}

.service-more-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 18px;
  margin-top: 8px;
  background: var(--color-bg-secondary);
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.service-more-toggle:hover {
  background: var(--color-border-light);
  color: var(--color-text);
}

.service-more-list {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-normal);
}

.service-more-list.open {
  max-height: 1000px;
}

/* ---------- Form ---------- */
.form-container {
  max-width: 560px;
  margin: 0 auto;
  padding: 0 22px 80px;
}

.form-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-sm);
}

.form-group {
  margin-bottom: 28px;
}

.form-label {
  display: block;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--color-text);
}

.form-label .required {
  color: var(--color-danger);
  margin-left: 2px;
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: 14px 16px;
  font-size: 16px;
  font-family: inherit;
  color: var(--color-text);
  background: var(--color-bg-tertiary);
  border: 1.5px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  outline: none;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 4px rgba(0, 113, 227, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 100px;
}

.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2386868b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  padding-right: 40px;
  cursor: pointer;
}

.form-checkbox-group {
  display: flex;
  align-items: flex-start;
  gap: 10px;
}

.form-checkbox {
  width: 20px;
  height: 20px;
  margin-top: 2px;
  accent-color: var(--color-accent);
  cursor: pointer;
  flex-shrink: 0;
}

.form-checkbox-label {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.5;
  cursor: pointer;
}

.form-checkbox-label a {
  color: var(--color-accent);
}

.form-summary {
  background: var(--color-bg-secondary);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 28px;
}

.form-summary-row {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
  font-size: 14px;
}

.form-summary-row .label {
  color: var(--color-text-secondary);
}

.form-summary-row .value {
  font-weight: 600;
  color: var(--color-text);
}

/* ---------- Success Page ---------- */
.success-container {
  min-height: calc(100vh - var(--nav-height));
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 60px 22px;
}

.success-card {
  text-align: center;
  max-width: 480px;
}

.success-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(52, 199, 89, 0.1);
  border-radius: 50%;
  font-size: 40px;
  color: var(--color-success);
  animation: successPop 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes successPop {
  0% { transform: scale(0); opacity: 0; }
  60% { transform: scale(1.1); }
  100% { transform: scale(1); opacity: 1; }
}

.success-title {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.success-desc {
  font-size: 17px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 36px;
}

.success-info {
  background: var(--color-bg-secondary);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 32px;
  text-align: left;
}

.success-info-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  font-size: 14px;
  border-bottom: 1px solid var(--color-border-light);
}

.success-info-row:last-child {
  border-bottom: none;
}

.success-info-row .label {
  color: var(--color-text-secondary);
}

.success-info-row .value {
  font-weight: 600;
}

/* ---------- Animations ---------- */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

.fade-in-delay-1 { animation-delay: 0.1s; }
.fade-in-delay-2 { animation-delay: 0.2s; }
.fade-in-delay-3 { animation-delay: 0.3s; }
.fade-in-delay-4 { animation-delay: 0.4s; }

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .nav-menu-btn {
    display: flex;
  }

  .hero {
    padding: calc(var(--nav-height) + 50px) 22px 60px;
  }

  .hero-title {
    font-size: 36px;
  }

  .hero-subtitle {
    font-size: 19px;
  }

  .section {
    padding: 60px 22px;
  }

  .section-title {
    font-size: 28px;
  }

  .section-desc {
    font-size: 17px;
  }

  .page-header {
    padding: calc(var(--nav-height) + 40px) 22px 36px;
  }

  .page-header h1 {
    font-size: 32px;
  }

  .os-grid {
    grid-template-columns: 1fr;
  }

  .form-card {
    padding: 28px 24px;
  }

  .skills-grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .skills-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
  }

  .hero-actions .btn {
    width: 100%;
  }
}